Fugitive druglord San Niang Thanga had been a rhino horn smuggler in the Northeast before joining the international drug cartel, called ‘125’.

Narcotics Control Bureau (NCB) officials made this revelation on Saturday in course of their probe into the drug racket, believed to be the Calcutta unit of ‘125’, that was busted on the ground floor of former CBI additional director Upen Biswas’ Salt Lake residence on May 19.

He was earlier found to have been involved in smuggling other wildlife products, like cheraw horn and pangolin skin.

According to NCB officials, who are now interrogating Thanga’s five associates — three Myanmarese and two Chinese — netted from Biswas’ house, Thanga used to work for an arms smuggling gang as well.

“Thanga had been caught while smuggling rhino horns and arms. He was booked under Wildlife Protection Act and Arms Act a year-and-a-half ago, but was granted bail later,” said an NCB official, adding that a Customs officer of superintendent rank and a lieutenant-colonel had helped him get bail. “We are talking to the authorities in the Northeast to trace them,” said an NCB sleuth.

Thanga’s “success” caught the attention of Kim Cheung Wong — the 57-year-old kingpin of 125, who was arrested a couple of weeks ago in China during an undercover operation launched by the US Drug Enforcement Agency. “Wong had picked up Thanga and assigned him to look after his business in the Northeast. Acting on Wong’s instruction, Thanga came to Salt Lake and set up the amphetamine-type stimulant manufacturing laboratory,” said an NCB official.